In Star Wars, the Rebel Alliance thought they were doing a good thing by destroying the Death Star. Little did they know the unintended consequences its destruction would have—notably, the complete and utter collapse of the Galactic Empire's economy.
The building of the death star would have sunk the star wars economy.
The death star was a planet sized gun, wasn't it? If so, every dime spent on it was essentially thrown away in an effort to throw away even more money as it blew up planets.
Unless it was a big factory, the empire's economy was screwed anyways. Destroying a weapon doesn't hurt an economy, it helps it. In fact, the scrap from the death star would re-allocate those resources and help revitalize an economy harmed to build the thing in the first place.
Of course, I'm no economist.